The 86th Annual Meeting of the American Association of Physical Anthropologists (2017)


Homo naledi posterior endocasts and their significance for understanding brain reorganization

RALPH L. HOLLOWAY1, SHAWN HURST2, HEATHER M. GARVIN3, TOM SCHOENEMANN4, WILL B. VANTI5, JOHN HAWKS6 and LEE BERGER7.

1Anthropology, Columbia University, 2Anthropology, Indiana University, 3Anthropology, Mercyhurst University, 4Anthropology, Indiana University, 5Science and Engineering Library, Columbia University, 6Anthropology, University of Wisconsin-Madison, 7Evolutionary Studies Institute, University of Witwatersrand

April 21, 2017 9:45, Bissonet Add to calendar

Abstract text: Of the more than 1550 Homo naledi fossil fragments discovered in the Dinaledi chamber of the Rising Star cave system, South Africa, seven fragments yield unusually well preserved endocranial morphology that permits identification of likely gyral and sulcal details. Here we describe and interpret the positive relief posterior endocranial features of these fragments as they relate to both the functional and taxonomic aspects of H. naledi. Endocranial descriptions are based on physical models as well as digital models and their curvature maps. These models were compared to early hominid endocranial casts, as well as human and chimpanzee endocranial casts, brain casts, and formalin fixed brains. Measurements and morphological features of these endocrania suggest that Homo naledi retained a lunate sulcus that was considerably smaller in extent than in chimpanzees, and that the dorsal remnant of the lunate was significantly reduced comparatively. The degree of occipital lobe asymmetry was pronounced on the left side of the preserved fragments, which in modern Homo sapiens is suggestive of right-handedness. Thus, while H. naledi had a small brain and some primitive retention of the pongid pattern of a lateral and anteriorly placed lunate sulcus, it nevertheless shows suggestions of the derived pattern of occipital lobe neural organization seen in modern Homo.

Funding statement: Funding for excavation and analysis was provided by the National Geographic Society, National Research Foundation of South Africa, and the Lyda Hill Foundation.